Study On Dynamic Characteristics Of Water Droplets Impinging On Low-Melting-Point Molten Metal

In metallurgical process,it is often accompanied by the interaction between the high-boiling-point hot molten metals and low-boiling-point coolant.Under certain conditions,the coolant evaporates rapidly in a short time and explodes,resulting in serious economic losses and casualties.Up to now,relatively few systematic studies have focused on this vapor explosion mechanism.Moreover,the technology cannot effectively protect from the vapor explosion.Therefore,in-depth study of the interaction between low temperature coolant and high temperature melt is very important to the theory and engineering application.In this paper,a small-scale experimental platform was designed and established to study the process of a droplet impacting on molten metal,by changing the Weber number(drop height and diameter of droplets),molten metals temperature and thickness,the degree of oxidation on the surface of molten metals and the type of molten metals,and so on.The results show that there are three typical phenomena of the interaction between water droplet and molten metal,e.g.Droplet breakup,Bubble and Crown.With the increase in the Weber number(drop height and diameter of the droplet)and the temperature of the molten metal,the maximum crown height increases,which implies that the vapor explosion is more violent.With the increase of the thickness of molten metal,the maximum crown height decreases first and then remains relatively stable.Although the oxidation layer reduces the probability of vapor explosion,the droplet and the oxidation layer are kept at an entrapping state,in other words,the upper,middle and lower parts of the droplet contact with air,oxidation and molten metal,resulting in the different evaporation rates.The cavity with rising pressure is formed under the oxide layer,which leads to more intense vapor explosion.Finally,through the comparison of water-tin and water-lead results,it is found that the density of molten metal has a significant effect on the vapor explosion.The higher molten metal density leads to relatively small maximum crown height and less violent vapor explosion.